Simple and Effective
I met with a client yesterday who, in an aside, revealed a system she's used for years.
She had a stack of large note cards secured with a rubber band. She had jotted down summaries of various subjects, such as team-building or strategic planning. Initially the cards were used to bone up for job interviews but she's added to the stack while on a series of jobs.
She described using them on long flights to review the key points she wanted to make at an interview or a meeting.